As a cutting tool for machining a work material such as metal, there has heretofore been a rotary tool constructed and arranged to detachably mount a cutting insert in an insert pocket disposed in a rotary tool body with a sheet member interposed therebetween (for example, refer to Patent Document 1).
The rotary tool described in the above publication is provided with a rotary tool body, a sheet member and a cutting insert. An insert pocket for mounting the insert with the sheet member interposed therebetween is disposed on the tip outer periphery of the rotary tool body.
The sheet member is made up of a body part having a top surface, a bottom surface and a plurality of side surfaces, and an upper shoulder part projecting from one end of the top surface. Thus, the sheet member has a stepped shape.
Through holes are formed in the middle part of the upper shoulder top surface and in the middle part of the other end of the top surface, respectively. The through hole formed in the middle part of the upper shoulder top surface is used for inserting a fixing screw that fixes the sheet member to the insert pocket. The through hole formed in the middle part on the other end of the top surface is used for inserting a fixing screw that fixes the sheet member and the insert to the insert pocket.
Thus, the above rotary tool has, as a fixing member, the fixing screw for fixing the insert to the tool body with the sheet member interposed therebetween, and the fixing screw for fixing the sheet member to the tool body. These fixing screws reduce unsteadiness of the insert.
However, the fixing screw used for fixing the sheet member is formed to be located only in the upper shoulder part, and hence increasing the sheet member size is unavoidable. This will cause the problem that the range occupied by the insert pocket for mounting the sheet member becomes large in the tool body, thereby deteriorating the strength of the tool body.
Patent Document 1: Japanese Unexamined Patent Publication No. 2004-237382